1. Field of the Invention
The present invention relates to a joining device, especially for concrete piles, and of the kind further defined in the preamble of claim 1.
2. Discussion of the Related Art
Concrete piles are commonly provided with a steel plate at each end. The steel plates cover the end surfaces of the concrete piles and may each form a part of an end cap of steel. When the concrete piles are to be joined to each other, this takes place through mutual anchoring of the steel plates, e.g. by means of bayonet joints or similar locking means. However, known locking means for the purpose concerned are expensive in production, cumbersome in use and often not without play.
Thus, in such known joining devices for concrete piles it is the end plates of steel that form the anchoring parts. The steel plates must, therefore, be dimensioned such that they can take up existing pressure stresses as well as existing tensile stresses and moments.
Furthermore, there is known a joining device for concrete piles wherein the piles at each end have a fastening body in each corner. This known joining device is voluminous, space-requiring and expensive.
Norwegian patent specification No. 140,170 concerns a joining device, especially for concrete piles, wherein pressure bodies in connection with wedges are used for the fastening. Also in this case, the pile ends are provided with steel plates or caps. At the other end, the pile is provided with a cavity the bottom of which forming rest for a wedge during its pressing-in into a split bolt, which is fixed in the co-operating pile end during the joining, such that the split bolt is wedged in the cavity by means of the wedge by the pressing-down of the upper pile. This known joining device is relatively complicated and requires great precision during the joining operation. It is emphasized that the wedge in this known joining device functions axially, i.e. in the longitudinal direction of the piles, therefore vertically. Such a wedge is, of course, not in a position to effect a desired pull of the two co-operating pile ends towards each other during the joining operation.